A long series of linear polyphosphates may be formed, the second of which is triphosphate ion, P3O105-. These species consist of PO4 tetrahedra with adjacent tetrahedra sharing a common oxygen atom at one corner. The structural formulas of
the acidic forms, H4P2O7 and H5P3O10, are given in figure3.12
It is easy to visualize the longer chains composing the higher linear polyphosphates. Vitreous sodium phosphates are mixtures consisting of linear phosphate chains with from 4 to approximately 18 phosphorus atoms each. Those with intermediate chain lengths comprise the majority of the species present